This laboratory has established that the pattern of T helper cell (Th) dysfunction seen in asymptomatic, HIV-seropositive (HIVs+) is also detected in patients with systemic lupus erythematosus (SLE). Thus, there are certain similarities between the immune dysregulation of SLE patients and HIV+ individuals. For example, mice immunized with the 16/6 idiotype exhibit a shift from a dominant type 1 to type 2 cytokine profile as they progress toward SLE. To investigate other possible similarities, we have tested the sera of SLE patients and mice with SLE-like diseases, and have found evidence of antibodies that recognize the gp120 of HIV, as well as certain synthetic peptides of HIV envelope. These results provide further evidence of similar immunodysregulatory events in SLE patients and individuals infected with HIV.